你的劝说对他毫无作用。

Your persuasion did not ___avail him at all.

别忘了利用图书馆资源来完成你的研究。

Don't forget to ___avail yourself of the library resources for your research.

她努力寻找丢失的钥匙，但毫无结果。

She searched hard for the lost keys, but it was to no ___avail.